Process for treatment of hydrocarbons



March 31, 1936. A. D. SMITH PROCESS FOR TREATMENT OF HYDROCARBONS Filed Nov. 23, 1931 E-Sheets-Sheet 1 arch 31, 1936. n- 2,035,727

PROCESS FOR TREATMENT OF HYDROCARBONS Filed Nov. 23, 1931 3 Sheets-Sheet 2 v March 31, 1936. A. D. S MITH PROCESS FOR TREATMENT OFHYDROCARBONS Filed Now/[23, 1951 s Sheets-Sheet s Patented Mar. 31, 1936 UNITE\ STATES rnocnss FOR. TREATMENT or HYDROCARBONS Arthur D. Smith, ChicagmIlL, assignor to Jenkins Petroleum Process Company, Chicago, 111.,

a. corporation of Wisconsin Application November 23, 1931, Serial No. 576,855

4 Claims.

=trade as gasoline.

\It is likewise known that the cracking rate doubles for a certain temperature increment rise over substantially the usual range of liquid phase cracking, and that such ratemay be maintained in vapor phase cracking by increasing such temperature increment.

In treatment in the latter phase,instead of attempting "to maintain the above mentioned cracking rate, I have found that under certain. cyclic circulative conditions, where a temperature and a time factor best suited for the particular hydrocarbons under treatment are employed, hydrocarbons of low anti-knock value may be transformed vinto hydrocarbons of higher antiknock rating; this especially applying to hydro-.

carbons of the straight chain, parafline and/or Y naphthene base series having a distillation range substantially equivalent to gasoline.

I do not attempt to explain whether such that of naphtha or transformation is due to the formation of isomers of the immediately above-mentioned hydrocarbon series, orto partial conversion into hydrocarbons of the benzeneor ring series,'but the fact remains that under the above described transforming treatment such conversion occurs; and that the transformed product has less tendency to' A general purpose of the inventionis to provid a process and apparatus for transforming hydrocarbons in vapor, or substantially vapor' phase, at a temperature and under a time factor best suited to increase the anti-knock value or- V bons with an otherwise minimum change in their 7 octane number of such hydrocarbons with a minimum volumetric loss.

A corollary'purpose of the invention is to effect such transforming treatment inhibitive of the production of permanent gas and/or carbon. '5

An important object of the invention is to provide a process and apparatus for the transformation of hydrocarbons of relatively low boiling point and initially low octane numberfin vapor,

or substantially vapor-phase, at a temperature lo and under a time factor, whereby such hydrocarbons will be converted into low boiling point hydrocarbons of higher octane number.

An auxiliary object of the invention is to conduct such preceding transformation on such hydrocarbons obtainingas aproduct of a previous cracking treatment.

A further auxiliary object of the invention is to conduct such preceding transformation directly on such hydrocarbons obtaining as a yaporous or substantially vaporous product of a previous cracking treatment.

Another object of the invention is to provide a process and apparatus whereby hydrocarbons of comparatively high boiling point are subjected to cracking treatment; and relatively low boiling point hydrocarbons obtained thereby are treated in 'vapor, or substantially vapor phase, at a temperature and under a time factor. best suited to increase the octane number of the relatively low boiling. point hydrocarbons so treated.

A specific object of the invention is to provide a process and apparatus :for' the continuous cyclic treatment of hydrocarbons .in vapor, or

I substantially vapor phase, at a temperature, and

under a time factor and pressure best suited to increase the octane number of said hydrocar physical characteristics.

I attain the'above described objectives by subjecting the hydrocarbons to be treated while in a. vapor, or substantially vapor phase, to continuous cyclic'circulation under a constant temperature, transforming time factor and pressure best suited toeifect the desired increase in octane number consistent with a minimum production of by-products, such as polymerized hydrocarbons of high boiling point, permanent gas and/or carbon.

, While the specific temperature, time factor and pressure employed will vary with the. hydrocarbons processed, the temperature range will lie between 800-l400? F. and the pressure between 0-500 lbs; the temperature and time fac- 66' heat per'unit volume of cyclically circulating such temperature during such cyclic circulation through absorption of minimum increments of vapor.

While in liquid phase cracking "a body of cyclically circulating oil may exist in liquid phase simultaneously and distinct from the reaction products existing in vapor phase, there is no such separation .in vapor phase cracking.

' To efi-ect the above mentioned cyclic circulation and at the same time maintain'a constant volume flow of vapor through the cracking means, which may be preferably of multi-tubular construction, I introduce niierein a circulating means, preferably a multi bladedfan of' turboimpeller type, having a relatively largev circulative ratio to a unit volume of flowing vapor; thus being able to effect within a flowing vapor stream a degree of internal cyclic circulation in proportion to the ratio between circulative and free flow volume. In other words, I dominate a; continuous vapor flow through the cracking means by internal cyclic circulation, and am thus able at one and the sametime, to maintain a constant temperature throughout said cracking means, a constant volume vapor flow therethrough, and to reduce the heating surface contact time per unit of circulatingvapor substantially in proportion to the cyclic circulative'throughput volume ratio. An important sequence of such cyclic ciroulative treatment is a reduction in the heating surface of the transforming means, thus efiecting a substantial saving in installation cost.

After release from the cyclic transforming means, the hot, superheated vapor is conducted to a non-extraneously heated transfer drum where, through the agency of therein introduced cooling oil, preferably of relatively low octane value and substantially vaporizable at the temperature obtaining (for example, the charging stock supplied to the cyclic transforming means or crude oil), said superheated vapor is reduced to an equilibrium temperature inhibitive of the production of undesirable decomposition products, but formative of an increase in octane value of said cooling oil.

Polymerized hydrocarbons of relatively high boiling point formed during the reaction may be withdrawn from the transfer drum as a liquid residuum and subjected to further refining treatment, or employed as fuel, or completely re- I moved from the system as may be desired.

The main vaporous fraction released from'the transfer drum may be directly subjected separately, or admixed with a hydrocarbon of higher octane number'" than the charging stock suppliedto the cyclic transforming means, to dephlegmation in a bubble tower of conventional design, with subsequent recovery therefrom ofa liquid gasoline of high octane number and separation of permanent gas in a manner' well known in the art; or the main vaaosup'a'z porous fraction released from the transfer may be preferably brought into indirect heat exchange with the charging stock supplied to the cyclic transforming means, before subjection to said dephlegmation.

The immediately above mentioned hydrocarbon of higher octane number may be for example, a light gasoline fraction boiling under 350 F., obtaining from a previous refining treatment; and said admixture may occur prior to or after said heat exchange, and in the-latter instance before or after entrar ".e to said bubble tower; 'the point of admixture depending on the heat obtaining in the main vaporous fraction and the resistance of the admixed hydrocarbon to further increase in octane number.

The bubble tower bottoms may be subjected to further transforming treatment, or employed in part as cooling oil to effect the before mentioned equilibrium temperature; or such product may be further refined according to a known method, or withdrawn from the system as may be desired. g

The gasoline ultimately recovered as a distil late condensate from the bubble tower, will be materially higher in 'octane number than the raw material originally charged to the transforming -mea .ns,the exact increase in the speciflc example cited depending on the chemical nature-of said-raw material; and in general upon the physical and chemical composition of the raw stock processed, the transforming tem-' perature, time factor and extent of the cyclic circulation employed.

. As a variation of t e process, a plurality 0f the previously descr ed cyclic transforming means, each equipped with a circulating device of the type herein mentioned, may be employed in combination with synchronously operatedcharging and, release valves to eifect a predetermined degree of recycling within one transforming means without addition. of raw material thereto, or release of vapor therefrom, until said predetermined treatment has been completed; other transformingmeans receiving a vapor charge in such interval; said m ns 'operating'in 7 Fig. 3 is a'longit'udinal cross-section along the line AA of the apparatus shown in Fig. 1 as it appears positioned in a suitable furnace construction also shown in longitudinal cross-section.

Fig. 4 represents essentially in diagrammatic elevation the apparatus shown in Fig. 1, together with the "previously described transfer drum, dephlegmating and condensing means; with such assembly in combination with a liquid phase cracking apparatus of known type supplying the raw material to be transformed. Referring to the drawings, I is a cyclic transforming tube still, comprising anupper cross drum 2, and a lower cross drum 3, whose ends are closed by flanges 2' and 3' respectively.

Into

'serves to relieve any a 2,035,127 said drums are expanded the circulating tubes 4, I

Intermediate between, and respectively connected to the upper and lower cross drums 2 and 3 by nozzles l2, I2, l2" and l3, I3 is the circuiating means l4; said means forming with the cross drums 2 and 3, tubes 4, and manifold headers 5, a closed cyclic internal circuit.

The circulating means comprises a housing l5,

enclosing a multi-bladed fan It, rigidly mounted I on a "shaft I1, and driven by an electric motor ground fiue 3|, and stack 32.

I8 orother suitable source of power. The shaft I1 is supported by the thrust bearings l9, l9 and internal bearing 20, while the known type 'of oil cooled stufiing box housing 2| serves not only to effectively seal the rotating shaft n against the operating pressure, but lubricates the lnternal bearing 20 of said shaft by means of oil supplied by theiducts 22 leading from the annular cooling chamber 23, surrounding the stuff-- ing box 24. Cooling oil is introduced to the chamber 23 through line 25 and withdrawn through line 26; said cooling oil being supplied by any suitable means, such as a rotary pump, designed to operate under a pressure slightly in excess of that obtaining in the cyclic transforming means;

The latter assembly is mounted over a furnace of known type, comprising suspended arches 28, flue-gas ports 29, downcomers 30, return under- The burners 33 are adaptable for either liquid or gaseous fuel,

and preferably have their fuel supply automatically controlled by a known type of. thermostatic device 34, located in the release or transfer line 9.

The metal employed throughout the cyclic circuit is of heat resisting or special alloy steel suitable for the high temperatures involved, and all exterior surfaces thereof not exposed to furnace action are protected from heat loss by refractory insulation (not shown); such protection in the case of the manifold headers 5 taking the form of a suitably insulated metallic housing 21, provided with doors 21' which may be opened for tube inspection or cleaning purposes. The transforming means is also equipped with the usual indicating and/or recording gauges (not shown) commonly used in the art for registering temperature and pressure.

Passing to the more general vaspects of the invention, and referring to Fig. 4; 35 designates a known type of liquid phase cracking still fromwhich the cracked vaporous products are conducted by the vapor line 36 to the blame tower 31, maintained under the full still pressure, and from which tower reflux condensate is returned to said still by the reflux line 38. The partially dephlegmated crude gasoline vapor separated in said baffle tower may be conducted by line 39, with flow and pressure drop controlled by the pressure release valve 40, into the dephlegmating or bubble tower 4|, with the reflux condensate or heavy naphtha therefrom forming the chief source of 'raw material for the transforming process herein described; or the bubble tower 4| may be elimi-' nated, and the crude gasoline obtaining from the baffle tower 31, with control therefrom effected by valve 40', directly employed as the chief source of raw material.

It is to be understood that the still 35 maybe replaced by a known type of vapor phase cracking still, or a non-cracking, shell, or tube still;

in short, any apparatus'capable 'ofcontinuously supplying the raw material to be transformed in vapor or substantiallyvaporous form, or at a temperature where such material may be readily vaporized. J

In the combination herein described, I employ crude gasoline or naphtha directly obtaining subsequent cyclic transforming process, where said crude gasoline or naphtha, when subjected to fractional distillation, showsthe lowboiling fractions obtaining thereby do not differ materially in octane number from the intermediate or residual fractions.

Where however a distillation test indicates the low boiling fractions to be of relatively higher.

octane numbe than the intermediate or residual fractions, I prefer to first separate the said low boiling fractions and conductthe' cyclic transforming treatment on the intermediate and/or residual fractions; or in the practical application of the process, to maintain such temperature at the top of the bubble tower 4| by a suitable dry or wet trim coil, that only low boiling fractions of relatively high octane number escape therefrom as vapor, and the remainder of the gasoline is condensed therein to form raw material for cyclic transformation.

Such raw material is withdrawn from the bubble tower 4| through the line 42, and by means of the high pressure pump 43, whose speed is preferably controlled by the float mechanism 44, is forced through line (in which a flow meter .46 may be interposed), lines 41,48, and 1, past checkvalve 49 and control valve 8 into the cyclic transforming means I; with said 'raw material being preferably preheated by passage through the heat exchanger 50 to a vaporous or substantially vaporous condition.

Crude gasoline or naphtha vapor obtaining directly from the baflle tower 31, when employed as raw material is conducted through line'39, as con-.

trolled by valve 40', through line 41 and'thence to the cyclic transforming means as above described; the pressure in the baiile tower 31 being usually sufficient to force the vapor directly into the transforming means under the pressure there obtaining without interposed compression means, whichhowever may be employed where necessary.

Converted vapor is released from the cyclic transforming means I through the line 9, as controlled by valve lil, to enter the transfer drum 5|, where said vapor is cooled by contact with a relatively cold hydrocarbon, to the previously described equilibrium temperature, said cooling hydrocarbon being introduced into said drum through the line 52 terminating in the perforated spray coil 52.

The cooling hydrocarbon may be a fractional portion of the raw material flowing through line 41, diverted therefrom through the branch. line 53, as controlled by valve 53' connecting to said 'line 52. An interposed cooling means 54 serves to lower the temperature of the cooling hydrocarbon it such be desirable. The cooling hydrocarbon may be a condensate from the bubble tower 55,

from the baffle tower 3'! as raw material for the? additional or other cooling hydrocarbon such as.

Crude oil for example, may be supplied to transfer drum 5| by a source without the system through hne 63, as controlled by valve 51', feeding pump 59. It is to. be understood that any mixture of the'cooling hydrocarbons herein mentioned may-be employed under suitable valve manipulation in a manner that will'be apparent to one skilled in the art.. Condensate from tower 55 may be withdrawn through cooling coil 64, as controlled by valve 58', and removed from the system; or suchtcondensate, controlled by valve 58, may be forced by pump 65 through line 66 to the baille tower 31.

Balanced valves (not shown) may be installed in lines 56' and 63, operated'by suitable float mechanisms in connection with the bubble tower 55, so that a constant liquid level .will obtain therein, and at the same time an adequate quantity of cooling hydrocarbon will be supplied to pump .59. I j

Liquid residuum is discharged from the transfer dnun 5| through line 61, and may be withdrawn from the system through cooling coil 68 as controlled by valve 69; or such residuum may be forced by pump as controlled by valve 69 through line 1| to baflle tower 31.

Transformed vapor obtaining in transfer drum 5|, cooled to the equilibrium temperature herein mentioned, is released through lines 12 and 14, as controlled by valves 13 and 13', through heat exchanger housing 58', to effect indirect heat exchange withthe raw material (whichif not already in vaporous condition attains such phase in such heat transfer) and then entersthe bubble tower 55 through line the control valves 13, 13' permitting by-passing of the transformed .vapor in any desired degree direct to said bubble tower 55.

Relatively high octane number gasoline vapor escaping from bubble -to wer through line 16, as controlled by valve 16, may be conducted through lines 11 and 1, as controlled by valve 98 and check valve 98, and thence forced by compressor 99 to the cyclic transforming means I;

I or said gasoline vapor may be conducted through line 11 as controlled by valves 18, 18', to the condenser 19 and thence to accumulating drum 80, where permanent gas is released through line 8|, as controlled by relief valve 8| set at a predetermined pressure. Liquid gasoline may be withdrawn from the system through line 82, as

controlled by valve 82', or such gasoline may flow through line 83, as controlled by valve 83', to

pump 84, and be thencedelivered through-lines 85 and 86 as controlled by valves 81. and 811 to the bubble tower 4| as a trim; or such gasoline may be employed wholly or in part as a liquid trim for bubble tower 55, discharging thereto through lines 85 and 88, as controlled by valves 81, 89" and 89'. i

In lieu of the above practice the gasoline vapor of high octane'number from bubble tower 4| may be conducted through line 11 as controlled by valves 98, 98' to line 15 and commingle with the vapor obtaining from transfer drum 5| before introduction into the bubble tower 55; or with a different adjustment of said valves 98, 90' said gasoline vapor, commingled with high octane number gasoline vapor "escaping from bubble tower 55 through line 9| as controlled by valve 9|, may be condensed incondenser 92 and the condensate therefrom conducted to accumulating drum 93, where permanent gas is, released through line 94 as controlled by valve 94' set at a predetermined pressure. Liquid transformed gasoline of high octane number may be withdrawn from the system from said drum 98, through line 95 as controlled by valve 85, or a portion of such gasoline may flow through line 96 as controlled by 96', to pump 91; and thence be delivered through line 85' as trim stock to bubble towers 55 M4 I, under the respective control of valves 89, 89' and 81", 81'.

The immediately' -above described connections transforming and liquid phase treatment. Such result is attained in the combination herein described, sometimes with the major portion of the aforesaid trim stocks fed to the liquid phase bubble tower, and at other times to the transforming means bubble tower; the effect being seemingly dependent on the nature of theraw and intermediate materials, temperatures and time factors employed in the process steps, and

' to a less extent on the pressure involved.

The invention is not limited in its process application to the type or arrangement of the ,in--

strumentalities herein described; nor are such instrumentalities as are herein claimed limited to any one process, nor to the precise form and relational size between parts as indicated by the drawings; and what I claim is new and desire to protect by Letters Patent is:

1. A process for increasing the octane number of hydrocarbon vapors which comprises conducting said vapors to a dephlegmating zone and therein separating out heavier fractions as a condensate leaving in vapor form desired light fractions, conducting a portion of said condensate of heavier fractions to' a vaporizing zone and therein substantially revaporizing said condensate, subjecting the revaporized condensate to vapor phase cracking by cyclicly circulating it through a heated, closed ring, continuously withdrawing a portion of the products of such vapor phase cracking reaction relatively small in proportion to the volume Lnder cyclic treatment, continuously replacing such withdrawn portion by additional revaporized condensate, immediately commingling the withdrawn portion with hydrocarbon oils at a lower temperat e to reduce the temperature of said withdrawn rtion to a temperature preventive of the formation of free carbon, separating vapors from the resultant mixture, and passing said vapors in indirect heat interchange with said condensate of heavier fractions in said vaporizing zone to substantially revaporize said condensate asaforesaid.

2; A process for increasing the octane number of hydrocarbon vapors which comprises subjecting hydrocarbon oils .to a cracking reaction under pressure in liquid-vapor phase to evolve vapors evolved to a fractionating zone and therein condensing out a heavy condensate portion, conducting the remaining vapors to a dephlegmating zone and therein separating out heavier fractions 'from said vapors as a condensate, removing a tinuously withdrawing a portion of the products.

of such vapor phase cracking reaction while continuing to impose said cyclic cracking conditions on the remaining portion, continuously replac-v ing such withdrawn portion by additional revaporized condensate, immediately commingling the withdrawn portion with hydrocarbon oils at a sufficientlylow temperature to inhibit formation of free carbon, separating vapors from the resultant mixture, and passing said vapors in indirect heat interchange with said condensate of heavier fractions in said vaporizing zone to substantially revaporize'said condensate as aforesaid.

3. A process for increasing the octane number of hydrocarbon vapors which comprises subjecting'hydrocarbon oils to a cracking reaction under pressure in the liquid-vapor phase to evolve vapors therefrom, separating and removing vapors so evolved to a fractionating zone and therein condensing out a heavy condensate portion, conducting the remaining vapors to a dephlegmating zone and therein separating out heavier fractions from said vapors as a condensate leaving in the vapor state gasoline vapors formed in the liquid-vapor phase cracking reaction, subjecting a portion of said gasoline vapors to cracking conditions in vapor phase, directly introducing the products of said vapor phase cracking reaction into a zone of lower pressure, immediately commingling therewith a portion of said condensate of heavier fractions to reduce the temperature of the products of said vapor phase cracking reaction sufficiently to prevent formation of free carbon, and fractionating the mixture of oil products thus formed to obtain gasoline vapors of high octane number and heavier liquid condensates.

4. A process for increasing the octane number of hydrocarbon vapors which comprises subjecting hydrocarbon oilsto a cracking reaction underpressure in liquid-vapor phase to evolve vapors therefrom, separating and removing vapors so evolved to a fractionating zone and therein condensing out a heavy condensate portion, conducting the remaining vapors to a dephlegmating zone and therein separating out heavier fractions from said vapors as a condensate, removing a portion of the condensatethus formed to a vaporizing zone and therein substantially revaporizing said condensate, subjecting the revaporized condensate to vapor phase cracking by cyclicly circulating it through a heated, closed ring, continuously withdrawing a portion of the products of such vapor phase cracking reaction while continuing to imposesaid cyclic cracking conditions on the remaining portion, continuously replacing such withdrawn portion by additional revaporized condensate, immediately commingling the withdrawn portion with hydrocarbon oils at a sufficiently low temperature to inhibit formation of free carbon, fractionating the resultant mixture to obtain gasoline vapors of high octane number and heavier liquid condensates, and introducing said heavier liquid condensates into the hydrocarbon oils subjected. to said cracking reaction in the liquid-vapor phase.

ARTHUR D. SMITH. 

